1. Field of the Invention
This invention relates to a process for producing a hydrogensiloxane represented by the following general formula (I) or (II): ##STR3## wherein R represents a group selected from the group consisting of halogenated hydrocarbon groups, fluorine-substituted ether groups and hydrocarbon groups of at least 2 carbon atoms; and where a plurality of R groups exist, the R's may be either identical or different, Me represents the methyl group, n represents an integer of 1 to 3, and m represents an integer of 1 or 2.
2. Description of the Prior Arts
As a method of producing a hydrogensiloxane represented by the above general formula (I) or (II), methods based on an equilibration reaction of siloxane by use of an acid and methods based on co-hydrolysis of chlorosiloxanes have been known heretofore.
As a method based on the equilibration reaction by use of an acid, for example, there has been known a method of producing the hydrogensiloxane corresponding to m=1 in the above general formula (II) by an equilibration reaction of a siloxane compound represented by the following reaction formula (a): ##STR4## wherein R and Me are as defined above, and the same meanings will apply in all the formulas where Me appears hereinbelow.
There has been also known a method of producing the hydrogensiloxane corresponding to m=2 in the above general formula (II) by an equilibration reaction of a siloxane compound represented by the following reaction formula (b): ##STR5## wherein a is an integer of 3 or 4, and b is an integer of 1 or above.
As a method based on co-hydrolysis of chlorosilanes, methods in which a mixture of chlorosilanes represented by R.sub.4-n SiCl.sub.n and HSi(Me).sub.2 Cl is brought into co-hydrolysis are described in the following literature:
(A) U.S. Pat. No. 2,877,255 PA0 (B) U.S. Pat. No. 2,877,256 PA0 (C) R. Okawara, Kogyo Kagaku Zasshi (Journal of the Chemical Society of Japan, Industrial Chemistry Section), 60, 1398 (1957) PA0 (D) R. Okawara, M. Sakiyama, Bull. Chem. Japan, 29, 236 (1956)
However, according to the methods utilizing the equilibration reaction represented by the reaction formula (a) above, the disiloxane used as the starting material is left unreacted, resulting in a considerably low yield of the intended product. According to the methods utilizing the equilibration reaction represented by the above reaction formula (b), on the other hand, polysiloxanes with the number b being 2 or above are by-produced and, therefore, the intended trisiloxane (namely, the hydrogensiloxane corresponding to m=2 in the general formula (II)) cannot always be produced in a satisfactory yield.
Furthermore, the methods by co-hydrolysis of chlorosilanes as described in the above-cited references have the problem that hydrogensiloxanes produced by condensation of a plurality of R.sub.4-n SiCl.sub.n molecules would be by-produced.